Breast cancer screening a complex mix of benefits, risk

NEW YORK (Reuters Health) - A one-size-fits-all approach in
urging women to get mammography screening for breast cancer is
not supported by evidence, U.S. researchers say, and it sows too
much fear.

A series of articles in the Journal of the American Medical
Association (JAMA) reviews the risks and benefits of screening
mammography at different ages, and concludes women need more
tailored advice and better quality information than they're
getting.

Mammograms are generally linked to a reduced risk of dying
from breast cancer, though not equally for everyone, and the
tests are also associated with real harms, write Dr. Lydia Pace
and her coauthor in a review of the numbers on screening.

"I think it would be easier for everyone if there was a
clear pre-specified pathway with a given risk profile, but we
don't have that because our data is not perfect and everyone is
different," Pace, from Brigham and Women's Hospital in Boston,
told Reuters Health.

"I wish that we had more certainty," Pace said.

Pace and her colleague point out in their JAMA report that
an estimated 40,000 women die of breast cancer in the U.S. each
year.

The government-backed U.S. Preventive Services Task Force
(USPSTF) broke from many other organizations in 2009 and began
recommending women at average risk for breast cancer get
mammograms every two years starting at age 50.

The USPSTF's decision was based on evidence that screening
leads to more benefits among older women who are screened less
frequently, according to Pace.

Many U.S. organizations continue to recommend annual
mammograms starting at age 40, however, an editorial
accompanying the report notes that most other countries have
guidelines similar to the USPSTF recommendation.

For their review, Pace and her colleague gathered previous
studies that have examined the risks and benefits of mammograms.

They found that annual mammograms are tied overall to a 19
percent drop in breast cancer deaths, but that the actual
decrease depends on the age of the women.

For example, 190 invasive breast cancers would be diagnosed
if 10,000 women in their 40s receive mammograms every year. Of
those diagnosed, mammography would save about five lives but 25
women would die with or without the mammograms.

The number of diagnosed cancers, deaths and lives saved
would be slightly higher among 10,000 women in their 50s who get
yearly mammograms.

For women in their 40s and 50s, however, a decade of
screening would also see more than 6,000 false-positive results
and over 700 unnecessary biopsies.

In addition, of the 190 women in the same group of 10,000
who would be diagnosed with breast cancer after yearly
mammograms during their 40s, the researchers estimate that 36 of
those cancers would never have caused harm during the women's
lives.

That means those 36 women would have unnecessarily received
surgery, chemotherapy and other treatments without gaining
anything in return.

For women older than 70, screening decisions should also
take into account a woman's other health issues and her
reasonable life expectancy, according to Dr. Louise Walter, of
the University of California, San Francisco, and her coauthor
Dr. Mara Schonberg of Harvard Medical School.

In a separate article, they calculate that screening every
two years after age 70 would avert two breast cancer deaths
among every 1,000 women screened.

It would also yield 200 false positive results per 1,000
women screened and 13 cases of overdiagnosis - finding and
treating a cancer that would have done no harm - per 1,000 women
screened.

Once again, the researchers conclude, women need to talk
with their doctors about their individual risk and their
preferences, when it comes to making decisions on screening.

In their editorial, Drs. Joann Elmore and Barnett Kramer
suggest that too much advocacy for screening, and doctors' worry
about malpractice claims if they don't recommend screening, have
skewed conversations about the risks and benefits of
mammography.

They write, "patient fears and physician concerns are not
conducive to truly informed shared decision making about a
complex choice."

Doctors should be talking to women about their realistic
risk of being diagnosed with breast cancer. But that can be
difficult, according to Elmore, who is at Harborview Medical
Center in Seattle, and Kramer, from the National Cancer in
Bethesda, Maryland.

They write that women may hear they have a one in eight
chance of being diagnosed with breast cancer, but they may not
understand that is over their entire lifetime and does not mean
death.

"Indeed, women do have an increased fear and increased
perception of risk of breast cancer," Elmore told Reuters
Health. "This one in eight statistic sounds very scary."

"It's really hard to take all these numbers and put it into
something that's easy to digest," she said.

Elmore said women can use an online tool from the National
Cancer Institute that allows women to calculate their risk of
developing breast cancer during the next five years. (It can be
found here: http://1.usa.gov/1iXaZTV).

"We can encourage and share with them our thoughts, but we
shouldn't make them feel guilty or bad about the decision they
make," she said. "We should just try to help them so the
decisions are informed."